Conventional search engines typically rank search results using external information such as information from sources other than the webpages being ranked. For example, a conventional search engine may use the number of external links to a particular webpage to determine the importance of the particular webpage. The external links may reside in other sources (e.g., webpages, documents, etc.) and may direct a user to the particular webpage. In this manner, the conventional search engine may rank each webpage based upon a respective number of external links to each webpage.
Although external information is commonly used by conventional search engines to perform searches and rank webpages, it is often a poor indicator of the importance or value of each webpage. For example, there may be few or no external links pointing to a potentially important document, and therefore, the document may be not be returned or ranked lower than it should be by a conventional search engine. As another example, if a statue of a famous person has recently been defaced, a search using a conventional search engine for autobiographical information about the famous person may instead return a multitude of less-important results related to the defacing of the statue. As such, a user may be unable to locate webpages with more important or valuable information using a conventional search engine which relies on external information.